Ag2CO3 catalyzed aza-michael addition of pyrazoles to a, 0-unsaturated carbonyl compounds: A new access to N-alkylated pyrazole derivatives

An efficient Ag2CO3 catalyzed aza-Michael addition of pyrazoles to a, 0-unsaturated carbonyl compounds is developed. In the present of 5 mol% of Ag2CO3, the reaction smoothly occurs in DCE at 120 degrees C to afford a series of N-alkylated pyrazoles in good to excellent yields. It is noteworthy that N1-alkylated pyrazoles are obtained with high regioselectivity (N1/N2 up to above 25:1) when asymmetrically substituted pyrazoles reacted with a, 0-unsaturated carbonyl compounds. The method can also extend to gram scale.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

An efficient Ag2CO3 catalyzed aza-Michael addition of pyrazoles to α,β-unsaturated carbonyl compounds has been developed. Using 5 mol% of Ag2CO3 as catalyst, the reaction proceeds smoothly in DCE at 120 degrees C, giving a series of N-alkylated pyrazoles in good to excellent yields. Notably, N1-alkylated pyrazoles can be obtained with high regioselectivity (N1/N2 up to above 25:1) when asymmetrically substituted pyrazoles react with α,β-unsaturated carbonyl compounds. The method is also applicable on a gram scale.